Restoring a 1956 Friden STW 10 Mechanical Calculator
The Friden STW 10 is a wonderful, fully automatic, mechanical calculator, that can add, subtract, multiply and divide very large numbers. It is large, very fast and noisy, quite impressive when it gets going. This is one of the most difficult mechanical restoration I have gone through to date. This machine is complex and not modular at all. Everything is connected and interlocked to everything else. It is very difficult to take apart, and even more difficult to put back together. This particular 1950's machine, although in great cosmetic condition, was in terrible mechanical shape. It had several dozen hard stuck parts, a similar number of sluggish ones, and a few critical mis-adjustments. I cut out many of the restoration details, but this is still a 27 minute video that chronicles several weeks of work! But in the end I got everything to work again...
I scanned and uploaded the documentation I recovered here: